In general, an air conditioning system for a vehicle is adapted to set the interior temperature of the vehicle to be lower than the exterior temperature using a refrigerant, and includes a compressor, a condenser, and an evaporator to form a refrigerant circulation cycle.
A type of compressor, i.e. a reciprocating compressor includes a cylinder and a piston reciprocating within the cylinder and is commonly used in an air conditioning system for home, industry, or vehicles. A representative example of such a reciprocating compressor is a swash plate compressor.
In a swash plate compressor, a disk-shaped swash plate is installed on a drive shaft receiving power of an engine with the inclination thereof being varied or fixed in correspondence to rotation of the drive shaft and a plurality of pistons installed by interposing a shoe along the periphery of the swash plate linearly reciprocate within a plurality of bores formed in a cylinder block while the swash plate is rotating, whereby a refrigerant gas is suctioned or compressed to be discharged.
A valve plate configured to control the suction and discharge of a refrigerant gas in the process of suctioning or compressing and discharging the refrigerant gas is installed between the housing and the cylinder block.
Hereinafter, a general swash plate compressor will be described with reference to FIG. 1.
The swash type compressor of FIG. 1 includes a front housing A10 in which a front cylinder block A20 is embedded, a rear housing A10a coupled to the front housing A10 and in which a rear cylinder block A20a is embedded, a plurality of pistons A50 configured to reciprocate in a plurality of cylinder bores A21 formed in the front and rear cylinder blocks A20 and A20a, a swash plate A40 inclinedly coupled to a drive shaft A30 and coupled to the pistons A50 with a shoe A45 being installed along the outer periphery thereof, valve plates A60 installed between the front and rear housings A10 and A10a and the front and rear cylinder blocks A20 and A20a, and a muffler installed at an upper portion of the outer surface of the rear housing A10a and configured to supply a refrigerant fed from an evaporator into the compressor during a suction stroke of the piston A50 and to discharge the refrigerant compressed in the compressor A1 toward a condenser.
A refrigerant discharge chamber A12 and a refrigerant suction chamber A11 are formed respectively inside and outside a partition wall A13 in the front and rear housings A10 and A10a. Here, the refrigerant discharge chamber 12 is divided into a first discharge chamber A12a formed inside the partition wall A13 and a second discharge chamber A12b formed outside the partition wall A13 and communicated with the first discharge chamber A12a through a discharge hole. Accordingly, the refrigerant in the first discharge chamber A12a flows into the second discharge chamber A12b via the discharge hole A12c of small diameter, making it possible to damp a pulsation pressure due to a suction operation of the refrigerant and reduce vibration and noise.
Meanwhile, a plurality of suction passages A22 are formed in the front and rear cylinder blocks A20 and A20a so that the refrigerant supplied into the swash plate chamber A24 provided between the front and rear cylinder blocks A20 and A20a, and the second discharge chambers A12b of the front and rear cylinder blocks A10 and A10a are communicated with each other by a connecting passage passing through the front and rear cylinder blocks A20 and A20a. Thus, as the pistons reciprocate, the refrigerant is suctioned and compressed simultaneously within the bores A21 of the front and rear cylinder blocks A20 and A20a. 
The conventional swash plate compressor compresses a refrigerant through the following process.
The refrigerant supplied from an evaporator is suctioned into a suction portion of the muffler A70 and then is supplied into the swash plate chamber A24 between the front and rear cylinder blocks A20 and A20a, and the refrigerant supplied into the swash plate chamber A24 flows into the refrigerant suction chambers A11 of the front and rear housings A10 and A10a along the suction passages A22 formed in the front and rear cylinder blocks A20 and A20a. 
Then, the suction lead valve is opened during the suction stroke of the piston A50, and the refrigerant in the refrigerant suction chamber A11 is suctioned into the cylinder bores A21 through a refrigerant suction hole of the valve plate A60. During the compression stroke of the piston, the refrigerant in the cylinder bore A21 is compressed, and the refrigerant flows into the first discharge chambers A12a in the front and rear housings A10 and A10a through the refrigerant discharge holes of the valve plates A60 as the discharge lead value is opened. After the refrigerant in the first discharge chamber A12a is discharged to the discharge portion of the muffler A70 through the refrigerant discharge opening A72 of the muffler A70 via the second discharge chamber A12b, it flows into the condenser.
Meanwhile, after the refrigerant compressed in the cylinder bore A21 of the front cylinder block A20 is discharged to the first discharge chamber A12a of the front housing A10 and then flows into the second discharge chamber A12b, it flows into the second discharge chamber A12b of the rear housing A10a along the connecting passages A23 formed in the front and rear cylinder blocks A20 and A20a to be discharged to the discharge portion of the muffler A70 through the refrigerant discharge opening together with the refrigerant in there.
However, in the conventional compressor A1, the suction volume efficiency of a refrigerant is reduced by a loss due to suction resistance caused by the complex refrigerant passages, a loss due to the elasticity resistance of the suction lead valve during an opening/closing operation of the valve plate A60, etc.
Further, pulsation noise is generated when a suction lead and a discharge lead are opening or closed.
Furthermore, the suction lead and the discharge lead are damaged after long term use thereof, making it impossible to perform their own functions.
Meanwhile, a technology for reducing a loss due to an elasticity resistance of such a suction lead valve is disclosed in Korean Laid-Open Patent No. 2007-19564 (“a compressor”, hereinafter referred to as “Prior Art”).
The prior art relates to a compressor to which a drive shaft integrated suction rotary valve having no suction lead valve is applied and allows a refrigerant to enter cylinder bores through the interior of a drive shaft to reduce a loss due to a suction resistance.
In more detail, as illustrated in FIG. 2, the compressor according to the prior art includes: a drive shaft B150 on which a swash plate B160 is inclinedly coupled, having a fluid passage B151 through which a refrigerant flows, having at least one suction opening B152 communicated with the fluid passage B151 on the side of a swash plate hub to which the swash plate B160 is coupled, and having an exit B153 at a position spaced apart from the suction opening B152; front and rear cylinder blocks B130 and B140 in which the drive shaft B150 is rotatably installed, having a plurality of cylinder bores B131 and B141 on opposite sides of a swash plate chamber B136, and having suction passages B132 and B142 communicating shaft support holes B133 and B143 with the cylinder bores B131 and B141 so that a refrigerant suctioned into the fluid passage B151 of the drive shaft B150 can be sequentially suctioned into the cylinder bores B131 and B141 while the drive shaft B150 is rotating; a plurality of pistons B170 mounted to the swash plate B160 by interposing a shoe at the periphery of the swash plate B160 and configured to reciprocate within the cylinder bores B131 and B141 in conjunction with rotation of the swash plate B160; and front and rear housings B110 and B120 coupled to opposite sides of the cylinder blocks B130 and B140 and having discharge chambers therein respectively.
In the compressor of the prior art, after the refrigerant introduced through a suction port (not shown) is introduced into the interior of the drive shaft B150 through the suction opening B152 formed on the hub side of the swash plate B160, it is introduced into the cylinder bores B131 and B141 via the fluid passage B151 formed in the interior of the drive shaft B150.
According to the prior art, when a piston reaches a top dead point where compression is completed, almost all of the compressed refrigerant of high pressure is discharged to the refrigerant discharge chambers of the front and rear housings and some of the refrigerant is kept within the suction passage. Then, the refrigerant left in the suction passage in a state of high pressure impedes suction of a refrigerant (in a low pressure state) introduced into the suction passage to perform a suction stroke, making it difficult to perform a suction operation. Further, a sufficient amount of fluid cannot be securely suctioned due to a refrigerant flow resistance in the suction passage.